This invention relates generally to methods and apparatus for computed tomographic (CT) image reconstruction, and more particularly to weighting of data collected in a CT system.
At least one known computed tomography (CT) imaging system uses an in creased table speed to reduce scan time. An increased table speed reduces the quantity of data samples acquired along a plurality of helical trajectories within an image reconstruction space. A reduction in the quantity of data samples combined with a plurality of cone beam effects may produce an image with decreased image quality.
In one aspect, a method for reconstructing an image of an object utilizing a computed tomographic (CT) imaging system is provided. The CT system includes a radiation source and a multislice detector array on a rotating gantry, with the radiation source configured to project a beam of radiation through an object and towards the multislice detector array. The multislice detector array is configured to sense attenuation of the radiation passing through the object. The method for reconstructing an image includes helically scanning an object with a computed tomographic imaging system to acquire a plurality of views of projection data at a plurality of gantry angles and a plurality of cone angles, generating a plurality of cone angle dependent weights that are inversely correlated to an absolute value of a cone angle, and weighting the projection data using the cone angle dependent weights.
In another aspect, a computed tomographic (CT) imaging system for reconstructing an image of an object is provided. The computed tomographic (CT) imaging system includes a radiation source and a multislice detector array on a rotating gantry, with the radiation source configured to project a beam of radiation through an object and towards the multislice detector array. The multislice detector array is configured to sense attenuation of the radiation passing through the object. The imaging system is configured to helically scan an object with a computed tomographic imaging system to acquire a plurality of views of projection data at a plurality of gantry angles and a plurality of cone angles, generate a plurality of cone angle dependent weights that are inversely correlated to an absolute value of a cone angle, and weight the projection data using the cone angle dependent weights.
In still another aspect, a computer for collecting computed tomography (CT) scan data is provided. The computer is programmed to helically scan an object with a computed tomographic imaging system to acquire a plurality of views of projection data at a plurality of gantry angles and a plurality of cone angles, generate a plurality of cone angle dependent weights that are inversely correlated to an absolute value of a cone angle, and weight the projection data using the cone angle dependent weights.